Salinity and Temperature Tolerance of Eastern Oyster (Crassostrea virginica) Larvae from the Northwest Coastal Region of Florida

Florida eastern oyster (Crassostrea virginica) populations have historically supported valuable wild fisheries; however, populations have collapsed across this region, including the previously highly productive Apalachicola Bay, FL. Estuaries are being affected by development, water management, and climatic changes, all of which can impact the sensitive early life history stages of this foundation species. This study provides information on physiological tolerances to the environmental conditions of larval eastern oysters from the Florida panhandle. Wild oysters from this area were used to produce larvae, which were cultured at a range of salinities (5, 8, 11, 14, 17, 20, 23, 26, 29, and 32) in 2023 and temperatures (14°C, 16°C, 18°C, 20°C, 22°C, 24°C, 26°C, 28°C, 30°C, and 32°C) in 2024. Survival and growth were measured throughout both culture periods. Salinity and temperature significantly affected larval survival and growth rates. Optimal survival and optimal growth occurred at different salinity and temperature values, indicating there may be tradeoffs between larval growth and survival in this region. This study provides key physiological information needed to understand eastern oyster biology and population dynamics in the Florida Panhandle region. Additionally, this study demonstrates potential physiological tradeoffs for larval eastern oysters across gradients in salinity and temperature, which are known to be highly variable across estuaries where eastern oysters reside.